97443-88-4Relevant academic research and scientific papers
Highly diastereoselective radical reactions of substituted methylideneimidazolidinones and related systems
Adamson, George A.,Beckwith, Athelstan L.J.,Chai, Christina L.L.
, p. 629 - 633 (2004)
Stannane-mediated radical addition to tnethylideneimidazolidinones occurs with good to excellent diastereo-selectivity. The stereochemical outcome of addition is highly dependent on the nature of the NI substituent on the imidazolidinone ring.
New Amino Acids for the Topographical Control of Peptide Conformation: Synthesis of All the Isomers of α,β-Dimethylphenylalanine and α,β-Dimethyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic Acid of High Optical Purity
Kazmierski, Wieslaw M.,Urbanczyk-Lipkowska, Zofia,Hruby, Victor J.
, p. 1789 - 1795 (2007/10/02)
The synthesis of all four diastereomers of α,β-dimethylphenylalanine (4) as well as those of α,β-dimethyl-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (5 and 6) have been accomplished in high yield and high optical purity.Molecular mechanics calculations on the Nα-acetyl and N-methylcarboxamide derivatives of (3R,4R)-6 and (3R,4S)-5 indicate large and moderate energy stabilization for the gauche(-) but not the gauche(+) side-chain conformers of (3R,4S)-5 and (3R,4R)-6, respectively.By symmetry rules, the same holds for (3S,4R)-5 and (3S,4S)-6, respectively.Thus, these amino acids are potential building blocks for the topographical design of peptides (Kazmierski et al., J.Am.Chem.Soc. 1991, 113, 2275-2283) by providing acylated 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives in which a gauche(-) and not a gauche(+) side-chain conformation is energetically more stable for the L amino acid.Synthetic details and implications of these new amino acids for peptide and protein design are discussed.
Addition of Chiral Glycine, Methionine, and Vinylglycine enolate Derivatives to Aldehydes and Ketones in the Preparation of Enantiomerically Pure α-Amino-β-hydroxy Acids
Seebach, Dieter,Juaristi, Eusebio,Miller, David D.,Schickli, Christof,Weber, Theodor
, p. 237 - 261 (2007/10/02)
Chiral enolates of imidazolidinones and oxazolidinones from the title amino acids react with carbonyl compounds to afford the corresponding alcohols in excellent yields (see Scheme 5).Furthermore, the addition to aldehydes proceeds with high diastereoselectivity to give, after acid hydrolysis, threo-α-amino-β-hydroxy acids of high enantiomeric purity.Some of the threo-α-amino-β-hydroxy acids prepared in this work are the proteinogenic (S)-threonine (26), the naturally occuring (S)-3-phenylserine (28), and (S)-3-hydroxyleucine (27) as well as the unnatural (S)-4,4,4-rtifluorothreonine (30) and (S)-3-(4-pyridyl)serine (31).The N-methylamide of (2S,3R,4R,6E)-3-hydroxy-4-methyl-2-(methylamino)-6-octenoic acid (32), the uniqe amino acid in the immunosuppressive cyclosporine, was prepared by the new method.This report presents also information suggesting that both steric and stereoelectronic effects are responsible for the good stereoselectivities observed.
Process for the enantioselective production of α-alkylated, acyclic α-aminocarboxylic acids
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, (2008/06/13)
α-Alkylated, acyclic α-aminocarboxylic acids of the formula STR1 where * represents a center of asymmetry, R1 is a lower alkyl, allyl, benzyl or substituted benzyl group and R2 is a lower alkyl, methoxymethyl, lower alkylmercaptoethy
105. The Chiral Glycine Enolate Derivative from 1-Benzoyl-2-(tert-butyl)-3-methyl-1,3-imidazolin-4-one is Alkylated in the 5-Position with Relative Topicity lk
Seebach, Dieter,Miller, David D.,Mueller, Stefan,Weber, Theodor
, p. 949 - 952 (2007/10/02)
An overall enantioselective substitution of the R-group of an α-hydroxy- or α-amino acid 1 by another R-group is possible through heterocycles 2 obtained from 1 with pivalaldehyde (1->7).The rac- and the (S)-(+)-heterocycles 8 (title compou
Herstellung enantiomerenreiner cis- oder trans-konfigurierter 2-(tert-Butyl)-3-methylimidazolidin-4-one aus den Aminosaeuren (S)-Alanin, (S)-Phenylalanin, (R)-Phenylglycin, (S)-Methionin und (S)-Valin.
Naef, Reto,Seebach, Dieter
, p. 135 - 143 (2007/10/02)
In contrast to α-hydroxy and α-mercapto carboxylic acids, simple α-amino acids do not form acetal-type derivatives (2, X=NH) with pivalaldehyde.For the generation of amino-acid-derived chiral, nonracemic enolates (cf.3), and hence, for the α-alkylation of amino acids without racemization and without an external chiral auxiliary, the imidazolidinones 12-14 were prepared diastereoselectively.To this end, the methyl or ethyl esters of amino-acid hydrochlorides were first converted to N-methylamides of amino acids which in turn were condensed with pivalaldehyde to give (neopentylidenamino)amides (11).These Schiff bases could be cyclized either to trans- or to cis-imidazolidinones (12, 14 and 13, respectively), which were obtained in enantiomerically pure form after recrystallization.The enantiomeric purities were confirmed by HPLC with chiral stationary phases or by 1H-NMR spectroscopy in the presence of chiral shift reagents.The configurations (cis, trans) were assigned by NOE measurements on 300- or 360-MHz 1H-NMR spectrometers.
